Field of the Invention
The present disclosure relates to a highly fluorinated photoresist employing a photodimerization chemistry and a method for manufacturing an organic light emitting diode display using the same.
Discussion of the Related Art
Nowadays, various flat panel display devices are developed for overcoming many drawbacks of the cathode ray tube such as heavy weight and bulk volume. The flat panel display devices include the liquid crystal display device (or LCD), the field emission display (or FED), the plasma display panel (or PDP) and the electroluminescence device (or EL).
FIG. 1 is a plane view illustrating the structure of the organic light emitting diode display (or ‘OLED’) having active switching elements such as thin film transistors according to the related art. FIG. 2 is a cross sectional view illustrating the structure of the OLED along to the cutting line of I-I″ in FIG. 1 according to the related art.
Referring to FIGS. 1 and 2, the OLED display comprises a thin film transistor (or ‘TFT’) substrate having the thin film transistors ST and DT and an organic light emitting diode OLED connected to and driven by the thin film transistors ST and DT, and a cap ENC joining the TFT substrate with an organic adhesive POLY (not shown) therebetween. The TFT substrate includes a switching thin film transistor ST, a driving thin film transistor DT connected to the switching thin film transistor ST, and an organic light emitting diode OLED connected to the driving thin film transistor DT.
On a transparent substrate SUB, the switching thin film transistor ST is formed where a gate line GL and a data line DL cross each other. The switching thin film transistor ST selects the pixel which is connected to the switching thin film transistor ST. The switching thin film transistor ST includes a gate electrode SG branching from the gate line GL, a semiconductor channel layer SA overlapping with the gate electrode SG, a source electrode SS and a drain electrode SD. The driving thin film transistor DT drives an anode electrode ANO of the organic light emitting diode OD disposed at the pixel selected by the switching thin film transistor ST. The driving thin film transistor DT includes a gate electrode DG connected to the drain electrode SD of the switching thin film transistor ST, a semiconductor channel layer DA, a source electrode DS connected to the driving current line VDD, and a drain electrode DD. The drain electrode DD of the driving thin film transistor DT is connected to the anode electrode ANO of the organic light emitting diode OD.
As one example, FIG. 2 shows the thin film transistor of top gate structure. In this case, the semiconductor channel layers SA and DA of the switching thin film transistor ST and the driving thin film transistor DT are firstly formed on the substrate SUB and the gate insulating layer GI covering them and then the gate electrodes SG and DG are formed thereon by overlapping with the center portion of the semiconductor channel layers SA and DA. After that, at both sides of the semiconductor channel layers SA and DA, the source electrodes SS and DS and the drain electrodes SD and DD are connected thereto through contact holes penetrating an insulating layer IN. The source electrodes SS and DS and the drain electrodes SD and DD are formed on the insulating layer IN.
In addition, at the outer area surrounding the display area where the pixel area is disposed, a gate pad GP formed at one end of the gate line GL, a data pad DP formed at one end of the data line DL, and a driving current pad VDP formed at one end of the driving current line VDD are arrayed. A passivation layer PAS is disposed to cover the upper whole surface of the substrate SUB having the switching and the driving thin film transistors ST and DT. After that, the contact holes are formed to expose the gate pad GP, the data pad DP, the driving current pad VDP and the drain electrode DD of the driving thin film transistor DD. Over the display area within the substrate SUB, a planar layer PL is coated. The planar layer PL makes the roughness of the upper surface of the substrate SUB in much smoother condition, for coating the organic materials composing the organic light emitting diode on the smooth and planar surface condition of the substrate SUB.
On the planar layer PL, the anode electrode ANO is formed to connect the drain electrode DD of the driving thin film transistor DT through one of the contact holes. On the other hand, at the outer area of the display area not having the planar layer PL, formed are a gate pad electrode GPT, a data pad electrode DPT and a driving current electrode VDPT connected to the gate pad GP, the data pad DP and the driving current pad VDP, respectively, exposed through the contact holes. On the substrate SUB, a bank BA is formed covering the display area, excepting the pixel area. Finally, a spacer SP may be formed over some portion of the bank BA.
A cap ENC is joined to the TFT substrate. In that case, it is preferable that the TFT substrate and the cap ENC are completely sealed by having an organic adhesive between them. The gate pad electrode GPT and the data pad electrode DPT are exposed and may be connected to external devices via the various connecting means.
As the needs for the organic light emitting diode display increase, and more advanced manufacturing technologies are developing, the technologies for the high resolution and large area organic light emitting diode displays has become underdeveloped. Until now, there are some methods for forming organic light emitting diodes on a large glass substrate, i.e., the fine metal mask (or ‘FMM’) patterning technology, the ink-jet printing technology, and the laser patterning technology. As an alternative method for manufacturing a large area organic light emitting diode display, a method for depositing one large white organic light emitting diode layer with a patterned color filter layer can also be used.
Using these patterning technologies or methods, it is possible to manufacture an organic light emitting diode display having large area and high resolution. However, the production yields and/or costs are not acceptable for mass production. In order to manufacture the pixel area of high resolution on a large area substrate, the most reasonable method is the photolithography method. There is still a critical problem for using the photolithography technology when patterning the organic light emitting materials. For example, the organic light emitting material can be easily damaged by the photoresist itself and the solvent used for developing and/or removing the photoresist.